Typically cellular communication networks are based on a fixed infrastructure for managing the radio communication within the network. In radio communication networks, such as the Long Term Evolution (LTE) or the LTE-Advanced (LTE-A) the fixed infrastructure comprises base stations (Node B, NB) or evolved NBs (eNB). The eNB is used to serve user terminals locating in the coverage area of the eNB. In order to facilitate the flexibility of the network and enhance the coverage area, also so called mobile cellular device-to-device (D2D), also referred to as mobile-to-mobile (M2M), machine-to-machine (M2M), terminal-to-terminal (T2T) or peer-to-peer (P2P), may be applied.
Basic idea behind the D2D is that mobile users can directly communicate with each other. The direct D2D communication comprises at least two relatively closely located devices communicating with each other directly instead of a conventional communication link for end-to-end (E2E) communication, in which the source device transmits data to the destination device via the eNB. The two devices in the D2D communication may apply radio resources of the mobile communication network, thus sharing the resources with devices that are communicating with the eNB in the conventional link. This way the users of the devices may obtain better quality of service (Qos), new applications and increased mobility support. The connections between the user equipment (u) participating in the D2D network, may be set up in an ad-hoc manner, with or without the control of the eNB. One of the fundamental to the D2D is to enable devices to discover each other and their services when the devices are within radio coverage of each other. For this, often applied solution is to have the devices broadcast some individual predefined beacons that are unique among the local network of D2D devices to advertise itself for node discovery.
Problem with the current practice arises when considering a D2D network employing devices, such as UEs, who are roaming around in large number and in unpredictable manner. Accordingly, it is cumbersome to ensure the large number of UEs to perform beaconing reliably with no or very little impact on the operation and performance of the cell of the eNB. Therefore, an improved solution is needed.